1. Field of the Invention
The present invention refers to a catheter device useful for percutaneous surgery of blood vessels and organs. The catheter uses radiant energy, such as laser high frequency or radiofrequency radiation, preferably for percutaneous cardiac surgery, such as valvotomy. It is also used for incision of membranous obstructions in blood vessels and hollow organs, especially in cardiac cavities. The catheter utilizes at least one light conductor, such as a waveguide, to transmit the energy radiation from its source to the point of emission of the radiation at a location close to the distal catheter tip. In a preferred embodiment by means of EKG timed and triggered pulsed radiant energy, the catheter is used to perform surgical procedures only when the cardiac valve is open.
2. Description of the Prior Art
Laser catheters for cardiac vessel surgery, such as is disclosed in U.S. Pat. No. 4,207,874, are being used to recanalize the interior of blocked blood vessels. Such catheters are discussed in Choy "Vascular recanalization with the laser catheter", IEEE Journal of Quantum Electronics, No. 12, 1984, pp. 1420-1426. In this prior device the catheter is percutaneously inserted into the blood vessel and its distal tip is advanced through the vessel up to the point of obstruction of the blood vessel caused by a thrombus or by an atherosclerotic plaque upon the walls of the blood vessel. During subsequent removal of the blockage by laser radiation, perforation of the vessel wall can occur, if the point of laser emission, typically located at the distal end of catheter tip, is not properly aimed at the obstruction of plaque or if the penetration depth of the laser light into the blood vessel exceeds the depth of the obstruction of plaque within the blood vessel.
A device to align the point of emission in a laser catheter was proposed for a catheter with an inflatable balloon at its distal end in U.S. Pat. No. 4,627,436 and in Nordstrom et al., "Laser angioplasty: controlled delivery of Argon laser energy" Radiology 167, 1988, pp. 463-465) centering or otherwise directing the laser radiation emitted from the fiber. The balloon in this device, however, completely obstructs the lumen of the blood vessel. In addition, the balloon can only be positioned in relatively narrow blood vessels and not in hollow organs, especially not in the cardiac cavity or at cardiac valves.
Furthermore, a laser catheter was employed in animal experiments to incise the septal cardiac muscle as noted in Isner et al. "The current status of lasers in the treatment of cardiovascular disease", IEEE Journal of Quantum Electronics, No. 12, 1984, pp. 1406-1418). The catheter in Isner was inserted percutaneously and advanced to the heart of dogs under echocardiographic guidance, where upon direct contact between the point of light emission and cardiac muscle the incision was possible, but selective positioning of the point of light emission at a predetermined location was not possible. Intraoperatively, a septal incision in a human heart was performed under direct vision.
From in-vitro experiments with postmortem specimen and from animal experiments, it is also known that laser catheters can be used to ablate membranous septum in the heart and to remove obstructions in large vessels, as noted in Riemenschneider et al., "Laser irradiation of congenital heart disease: Potential for palliation and correction of intracardiac and intravascular defects", Am Heart J 106, 1983, pp. 1389-1393). In the in-vitro experiments described in Riemenschneider the catheters were directly inserted into the specimen from the outside, while a relatively nonselective perforation of the cardiac septum could be performed in the animal experiments using a percutaneously inserted catheter.